Tubing Packer.—In wells like those of Okla homa and Kansas and in the Eastern oil fields or pools there is often gas with the wells. It may be desirous to force the gas out of the tubing with the oil; a gas packer is then inserted. One of the latest types is the gas packer shown in Fig. 54. This spiral packer is set in shale. The oakum packing is laid around the spiral which is then compressed by letting the weight of the tubing upon it. This makes a tight joint with the shale wall and keeps the gas from working upward and forces it through the gas cage and into the tubing. This is also used on gas wells.
Operating difficulties are better appre ciated when California practice is studied. In California, when a test has reached the oil sand and production is assured the hole is turned over to the well gang composed of four men.
These men proceed to put in the pump and tubing and other accessories. Once a new well is put on the pump the troubles just commence.
Each well must be treated differently. Some start pumping and give little trouble, others give a great deal. In many Cali fornia wells it is not unusual to have new pumps worn out within 12 hr. when pumping where great quantities of sand enter the hole.
It is often necessary to maintain crews on the well night and day to keep them pumping. Derricks are equipped with electric lights for night work.
Sometimes wells cause trouble for several weeks before settling down into steady pumpers.
Wells without screen pipe run from 7 to 20 days without renew ing pumps. After settling down, 15 days is a fair life for a pump on an average well 2 years old. After that time pumps must be renewed about every 30 days.
Sand Troubles.—In California and in the Gulf Coast area of Texas and Louisiana soft, unconsolidated sands are found. These sands flow into the wells with the oil and often fill the casing and clog the well pumps.
It is no uncommon sight to see hundreds of thousands of cubic feet of sand around the oil wells. Handling of this sand is expensive and very troublesome.
Sand causes decreased production due to: 1. Wearing out of pumps.
2. Clogging of wells.
3. Cleaning out operations.
4. Handling sand on surface.
Elimination of sand troubles means a great saving to the oil producer.
This can be accomplished largely.
1. By using a pump system that can handle the sand, 2. By using strainers or screens to prevent the inflow of sand, 3. By "cleaning-out" systems.
A pumping system for handling sand has been worked out along the following lines: 1. Use of steel plungers instead of leather cups in a working barrel.
2. Place the pump a hundred feet or more above the oil sand. Where wells are a few months old this system may work.
Cleaning out systems involve periodic "washing out" or "drilling out" of the sands that accumulate in a well. This may call for several days' or several weeks' work and is expensive in that the well is "off" for that period and that after wells are "on the beam" the trouble commences again.
Strainers or oil-well screens have eliminated a large percentage of sand troubles. The principle is merely to use perforations so screened that fine sand can enter the well but larger particles cannot.
Some oil producers claim that it is essential "to get the sand to obtain the oil." This idea is difficult to dislodge from some minds.
Certainly in those new fields where wells are flowing freely any form of perforation that would check the flow of oil sand would check the production of oil.
The question is still an open one and only a careful study of the whole question will determine the relative value of the systems.
Several types of screens are on the market.
Figure 55, page 130, shows a number of different types of screens. Figure 56 shows the setting of screen in the Gulf Coastal area of Texas with the rotary system.
The treatment of wells varies in a marked degree in various fields. In the Mid-Continent and Eastern fields the handling of wells is simple compared to the Gulf Coast, and to California con ditions. The softer unconsolidated sediments of the latter regions present a set of operating problems that must be solved in a different manner from the hard rocks of the East.
In the Mid-Continent and Eastern areas there is little or no sand with the oil. The presence of large quantities of free sand in the California wells makes it necessary to clean the wells oftener, requires a different pump plunger, and calls for closer watching of wells.
Gauging Oil Wells.—A careful gauge of each well is essen tial as a guide in estimating the proper time to repair the pump, or to clean out the well. In Eastern practice it has been considered sufficient to pump all the wells on a property into one tank and then gauge that tank. Conditions are such in some cases that this is sufficient. Individual gauges are desirable especially in making careful valuations of properties. In California, individual gauges have been taken for many years. A careful study of each well is most desirable in other regions than California where the wells may fall off entirely over night.